Combined volatile metabolome and transcriptome analysis of 60 peach cultivars provide new insights into the formation of aroma and the identification of associated genes

Volatile organic compounds (VOCs) are the main chemical compounds that determine the characteristic aroma and flavor of fruit. In this study, we identified a total of 97 VOCs, including 5C6 compounds, 12 aldehydes, 4 alcohols, 10 esters, 13 lactones, 18 terpenes, 8 norisoprenoids, 8 ketones, 3 hydrocarbons, 8 phenylalanine derivates, and 8 other compounds, in 60 peach cultivars using headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrophotometry (GCeMS). A wide range of VOCs were detected in these germplasm resources with respect to both quantity and concentration. Correlation analysis with different physiological traits demonstrated that the genetic background exerts a significant influence on the composition and content of VOCs among peach cultivars. For example, the content of norisoprenoid was significantly lower in yellow-fleshed peach than in white-fleshed peach, and lactones were almost undetectable in stony hard peach. Among the 97 VOCs, 26 exhibited odor activity values (OAVs) exceeding 1, suggesting that these compounds act as key odorants in the peach VOC composition. Moreover, six structural genes associated with the synthesis of g-decalactone and (Z)-3-hexenyl acetate and five genes linked to aldehyde and 1-octen-3-one biosynthesis were identified through weighted gene co-expression network analysis (WGCNA). Additionally, 15 transcription factors (TFs) were identified as potentially regulating VOC synthesis. Overall, these data provide insight into the factors contributing to the differences in aroma qualities among peach cultivars, which can help to promote the development of peach breeding.